1. Field of the Invention
This invention relates generally to a filtration system.
2. Brief Description of the Related Art
In general, various kinds of corruption factors are usually produced in a water tank for keeping aquatic animals and plants for hobby or ornamental purposes. For example, in a water tank for aquatic animals, water in the tank is often corrupted by discharged materials, bait or feeds, algae, seaweed, etc. If this condition is left as it is, the degree of clearness and transparency of the water and water tank are lowered. As a result, it becomes difficult for those who keep such aquatic animals to fully enjoy watching the aquatic animals. In addition, hazardous components such as ammonia, nitrogen and the like are increasingly produced to the extent that the aquatic animals are killed and plants are abnormally grown. In order to prevent such an unfavorable occurrence, various types of filtration systems are conventionally used for removing such corruption factors in the water.
Several types of filtration systems for a water tank for keeping aquatic animals and plants are known. One example is shown in FIG. 6, in which a filter medium 103 composed of only a single or several kinds of chemical fiber materials or a combination of sand-layers and filter, is received in a container 102 which is separately situated from a water tank 101, and the water in the tank 101 is drawn up by a motor pump 106 through an intake tube 105 having a meshed basket 104 at a lower portion of the tube 105 and discharged to the upper surface of the filter medium 103 in the container 102 via a discharge tube 107, and then allowed to flow back to the water tank 101 through a return tube 108. Another example is shown in FIG. 7, in which a filter medium is received in a container 109 having a plurality of inlet ports formed in a bottom surface or a side surface thereof, the container 109 is then placed on a bottom portion of a water tank 101, and an upper end portion of the container 109 is connected to a motor pump 111 through an intake tube 110, so that the water in the water tank 101 flows to and passes through the filter medium and then drawn by the motor pump 111 so as to be returned to the water tank 101 through a return tube 112. An additional example is shown in FIG. 8, in which the water in a water tank is drawn into a container 115 located outside the water tank by a motor pump 116 located in the top of the container 115 through an intake tube 114 having a meshed basket 114 on a bottom portion of the water tank, so that the water passes through a filter medium received in the container 115, and then flows back into the water tank through a return tube 117.
Incidentally, it is a general practice to deliver air into a water tank from an air pump located outside the water tank through a tube, in order to supply oxygen into the water.
However, any one of the above-mentioned conventional filtration systems employs as a solid-liquid separator only one clean filtration means or system, such as a filter (chemical fiber material, filter paper, etc.) and/or a particulated filter medium layer (sand layer). Since it is designed such that the water in the water tank flows directly to the filter medium to capture the corruption factors contained in the water by the filter medium, filtration efficiency is comparatively low.
That is to say, in any one of the above-mentioned conventional filtration systems, particulates as corruption factors are captured directly by the filter medium during the process of filtration. Therefore, as the amount of particulates captured by the filter medium is increased, the filter liquid flow path formed in the filter material is narrowed in a comparatively short time and finally completely choked whereby clogging is produced. Accordingly, in the example shown in FIG. 6, the non-filtered water drawn up by the pump merely passes across the surface of the filter medium and directly flows back to the water tank. Also, in the examples shown in FIGS. 7 and 8, since the speed of water passing within the filtration system is lowered due to clogging, there is produced a region where the water flow is weak or none, within the water tank. As a result, the corruption factors are precipitated on the bottom portion of the water tank and condensed into sludge which produces hazardous components. Then, the corruption factors in the form of sludge are caused to suspend or float within the water tank in accordance with the water flow produced by the aquatic animals swimming in the water of the water tank or air supplied to the water tank.
In order to prevent an early and complete choking or blocking of the filter surface caused by such corruption matters, it is necessary to have a large filtration area dimension. However, if the filtration area dimension is increased, a filtration system as a final product becomes large in size. Recently, there is a tendency that very tiny aquatic animals or plants are kept in a small-sized water tank. Therefore, there is demanded a small-sized filtration system having an excellent filtration efficiency, so as to match with such a small-sized water tank.
Further, since any one of the above-mentioned conventional filtration systems employs a motor pump in order to forcibly circulate water, costs of electric power are increased and noises are produced.
Furthermore, in the conventional filtration systems mentioned above, various attachments such as intake tube (104, 105; 113, 114) attached with a meshed basket, discharge tube (107), motor pump (106, 111, 116) and return tube (108, 112, 117) are essentially employed, in addition to the filter medium receiving portion (103, 109, 115) acting as a main body for exhibiting the filtration function. Accordingly, the appearance of the system is unsightly, and handling is not easy when cleaning.
The present invention has been accomplished in order to obviate the above problems inherent in the conventional systems.